Stimulation of corneal differentiation by interaction between cell surface and extracellular matrix: II. Further studies on the nature and site of transfilter “induction”
[摘要] Cornealepithelialdifferentiation(primarystromaproduction)isdependentontheunderlyingextracellularmatrix(ECM),forifthedevelopingepitheliumisenzymaticallyremovedfromtheembryo,itfailstoproducestromainvitrounlessitisculturedoncollagenousECM.WehavepreviouslyshownthatthestimulatoryeffectismediatedacrossNucleoporefiltersindirectproportiontothesurfaceareacreatedbyepithelialcellprocessestraversingthefiltertocontactECM.SincecollagenousECMisinsolubleunderphysiologicalconditions,transfilterstimulationofstromaproductionisprobablyduetoaninteractionoftheepithelialcellsurfacewith“inducerâ€ECM(killedlenscapsuleorpurifiedcollagen).Wegrew5-day-oldcornealepitheliaonNucleoporefiltersatop[3H]proline-labeledlenscapsulesandusedbothautoradiographyandscintillationcountingtoshowthatradioactivecollagendoesnotentertheepithelialcellsindetectableamounts.WealsoshowherethatthestimulatoryeffectofcollagenoncollagensynthesisisnotdependentontrappingofserumorbindingofconditionedmediumfactorsbyECM.Finally,wedemonstratethatthestimulatoryeffectisreducedbyremovaloftransfilterECMafter6–12hrinvitro.By18–24hr,however,culturedepitheliumislessdependentonthesubstratum,probablybecauseithasproduceditsownECM.Weconcludethat:(1)thecontactmediatedcollagen-cellsurfaceinteractionunderstudyhererequiresthecontinuouspresenceofcollageninvivoandinvitroformaintenanceof“stimulatedâ€epithelialstromasynthesis;(2)thecollagenous“inducerâ€interactsdirectlywithepitheliumratherthanindirectlyviatrappedintermediates;(3)collagenactsattheepithelialcellsurfacewithoutenteringthecells.
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[效力级别] [学科分类] 生物科学(综合)
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